Hot-wire sensors are utilized in various arrangements. For example, German published patent application DE-OS No. 27 29 743 discloses an arrangement for measuring the flow velocity of gases and German Pat. No. 25 05 689 discloses an arrangement for measuring the heat conductivity of a gas mixture. From the measurement of the velocity at a predetermined location in a conduit, it is possible to determine the material or volume throughput. This then is possible with a higher accuracy when the ratio of the measured velocity to the averaged flow rate is a constant or is at least a known function of the measured quantity. However, in order to achieve this condition, either very long stabilization intervals or intense constrictions of the flow channel or other arrangements are necessary for producing a uniform flow. These arrangements in general cause additional flow losses.
An arrangement for measuring the velocity and direction of a gas flow, especially for determining the vertical velocity of aircraft, is already known from the German published patent application DE-AS No. 15 23 270. In this configuration the measuring probe consists of two freely-supported windings each having the shape of a truncated cone. The windings are superposed at their smaller longitudinal end faces. The windings are utilized as resistance sensors in an electrical bridge circuit.